For example, prior arts of Patent Documents 1 and 2 discuss that aerogel containing 3 to 10 nm thick silica particles and pores of the order of 10 to 50 nm in size, when included between a board and light-emitting layer in an organic electroluminescence device, increases photoluminescence intensity and current efficiency of the element almost 2 times and 1.6 times, respectively. Prior art of Non-patent Document 1 discusses that aerogel, when included between a thin-film transistor board and transparent electrode in an organic electroluminescence device, increases current efficiency of the device by almost 60%.
Another prior art of non-patent Document 2 discloses an attempt to improve light extraction efficiency of an organic electroluminescence device based on a photonic crystal layer with a silicon nitride (SiN) film provided on a glass board and below a transparent electrode, and 7 to 400 nm deep patterns provided in the interface between the glass board and SiN film at intervals of 200 to 900 nm. It discusses that increasing depth of the pattern grooves can improve its light extraction efficiency by up to 50%.
Patent Document 1: JP-A-2001-202827
Patent Document 2: JP-A-2003-201443
Non-patent Document 1: Hiroshi Yokogawa, 9th Symposium, Organic Molecules and Bioelectronics Section, JSAP, 2001
Non-patent Document 2: Yong-Jae Lee, et. al, Appl. Phys. Lett., 82, 3779 (2003)